A radar device, using a distributed array antenna, is able to obtain high spatial resolution by performing beam forming, in which a digital beam forming (DBF) process or the like is implemented on output of a plurality of arranged sub-array antennas. The sub-array antenna is an array antenna constituted by a plurality of element antennas. The distributed array antenna is formed by arranging a plurality of the sub-array antennas to perform phase control. An antenna aperture size of the distributed array antenna is equivalent to an area where the plural sub-array antennas are arranged.
In the radar device using the distributed array antenna, it is required to perform processes for accurate estimation of antenna specifications, such as the arrangement relation among the sub-array antennas, the directionality of the aperture plane of the sub-array antennas, a relative transmission phase of the sub-array antennas, and the like. Those processes enable the radar device to achieve beam orientation directed to an accurate direction using the DBF, and accurate angle measuring processing. Conventionally, the estimation of the antenna specifications is performed by arranging a transmission source of reference radio waves whose position information has been acquired highly-accurately, and then receiving transmission radio waves from the transmission source (for example, position estimation of a sensor in Non-patent Literature 1 mentioned later). Specifically, the amplitude and phase of a signal from the transmission source, each of whose position has been acquired highly-accurately, are measured by each sub-array antenna, and a steering vector matching the measured amplitude and phase is searched for, thereby identifying the arrangement of a corresponding sub-array antenna.